Proceedings of SerbiaTrib '13

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Serbian TribologySocietySERBIATRIB ‘1313 th International Conference onTribologyKragujevac, Serbia, 15 – 17 May 2013Faculty of Engineeringin KragujevacMEASUREMENT INSTRUMENTATION FOR DETERMINATIONOF STATIC COEFFICIENT OF ROLLING FRICTIONPetar Todorović 1 , Ivan Mačužić 1 , Branislav Jeremić 1 ,Marko Đapan 1 , Branko Tadić 11 Faculty of Engineering Kragujevac, Serbia, petar@kg.ac.rs, ivanm@kg.ac.rs,bane@kg.ac.rs, djapan@kg.ac.rs, btadic@kg.ac.rsAbstract: This paper is considering the influence of temperature, at normal load and bend radius of contactelements on the coefficient of rolling friction. Contact pairs are made of steel DIN 17230 (100Cr6).Measurement results in a condition of high temperatures, variation of the normal load and bend radius ofcontact element indicate complex influence of temperature in this specific test condition. Authors’ futureresearch would be in direction of determination of static friction coefficient on the higher temperatures ofcontact pairs made of different materials.Keywords: Measurement instrumentation, coefficient of rolling friction, high temperatures, inclined plane1. INTRODUCTIONFor every engineer and constructor, who isengaged in design and development of mechanicalconstructions, knowledge of friction coefficient isvery important and crucial. However, there aremultiple issues, doubts and problems regardingusing of friction coefficient values duringexperiments. These problems occur primarilybecause of poor applying of standard tables andunder which conditions these values are measured.This is all because friction coefficient values aredifferent from laboratory to laboratory, and dependon equipment, measuring methods and a number ofother parameters that may influence on diversity ofmeasured values. Peter J. Blau [1] has representedreview of friction force and ways of itsmeasurement. He made a list of standardmeasurement methods for static and dynamicfriction coefficient as well as the way of itspotential use.As we know, friction occurs when two bodiesare in contact and based on velocity of relativemotion, friction can be static or kinetic. The staticfriction coefficient depends on many differentparameters, primarily from surface contact, normalload, atmosphere conditions and temperature,surface absorption, quality of processing andmaterial in contact [2-5]. There have been severalstudies regarding the influence of surface roughnessparameters with the static friction coefficient andconcluded that the coefficient of static friction willincrease if surface roughness coefficient increases[3, 4]. Also, some of them concluded that someroughness parameters, like skewness and kurtosis,have a greater influence on coefficient of staticfriction compared to other parameters [6, 7].Complete understanding of the coefficient of staticfriction is impossible without various analyses ofmechanisms under which this is occurring. Thisissue is a goal for numerous research efforts [8-10].As a start, some authors represented conditionsunder which the value of static friction is greaterthan the dynamic friction value, in terms oftemperature influence on creep motion. Generally,at temperature above zero, static friction coefficientis higher compared to kinetic friction coefficientdue to different heat activated processes. But, wecannot say that the static friction coefficient hasonly one value because it depends on contact andinitial velocity. In order to determine static frictioncoefficient, Chang et al. [8] analyzed adhesionforce and load in contact at rough metal surfaces.The study showed that the coefficient of staticfriction depends on characteristics of the materialand topography of the surface in contact as well asthat depends on external load versus generaldefined friction law. In this paper, researchers were396 13 th International Conference on Tribology – Serbiatrib’13
experimentally determined that for specific externalload, coefficient of static friction will decrease ifplastic characteristic of material increases andsurface energy decreases. D.-H. Hwang et al [11]concluded that the coefficient of static friction ishigher if contact pair is made of different material -steel/alumina, while the lower value is determinedfor similar materials (steel/steel). This result isconsequence of “stick-slip” effect. Also, one ofconclusions was that the influence of surfaceroughness has less influence for similar materials incontact pair, as well as the increasing value ofnormal load affects on increasing coefficient ofstatic friction in contact pair of different materials,while there is no significant influence for contactpairs of the identical materials.Etsion and Amit [12] experimentally researchedthe influence of normal load on coefficient of staticfriction with very smooth metal surfaces in acontrolled laboratory conditions. Dramaticallyincreasing coefficient of static friction was noticedwhen the normal load is on the lowest level.Behaviour like this is assigned to adhesion forceswhich have more important function regardingsmall normal loads and surface smoothness.A small number of papers deal with coefficientof static friction under influence of temperature[13-16]. The most important conclusion thatauthors made in this papers is that the coefficient ofstatic friction will increase if temperature isincreased, which is resulted of increasing plasticcharacteristics of the most contact material atincreased temperature. Reviewing the literature isnoticed that experimental tests of coefficient ofstatic friction were performed on experimentalequipment with different design, construction anddifferent contact geometry. Also, very interestingare measurement instruments for static coefficientof rolling friction [17-19]. Friction characteristicsof rolling bearing elements depend on contact pairmaterial, design, tolerance, topography of contactsurfaces and lubricants. Authors in this papernoticed, during literature review, that there are noany papers which based their research attempts onstatic coefficient of rolling friction, while inconditions at higher temperature referring to issueabove, there was no paper found (when this paper iswritten).The aim of this paper is to determine influenceof temperature on static coefficient of rollingfriction on contact elements made of steel.Experimental measurements were performed oninstrumentation that authors designed, developedand constructed regarding very precisedetermination of static coefficient of rolling frictionat higher temperatures and relatively small valuesof contact pressure with changing radius bends ofcontact elements.2. THEORETICAL CONSIDERATIONAccording to literature, the static coefficient offriction increases with increasing temperature. It isfound that temperatures above 200°C lead toincreasing of coefficient of friction which can beinterpreted as a result of increasing plasticcharacteristics of material at increased temperature.The static coefficient of rolling friction tested incondition of increased temperature has not beensubject of either theoretical or experimentalresearch. The authors will determine the influenceof temperature, normal load and radius bend ofcontact elements on coefficient of rolling frictionby experimental methods. According to that,measure instrumentation is designed andconstructed, based on inclined plane principle.In the case of rolling friction (contiguous case –figure 1), coefficient of rolling friction isdetermined from formula 1 and 2:where are:M N e(1)M PM moment of resistance andMP rolling moment.From equations 3 and 4: F R(2)eF N f N(3)Ref tanα(4)Rand from the body balance at inclined plate (figure2), we get the following equation:N G cosα(5)esinα R N e G cosα e tanα (6)Rwhere are:f static coefficient of rolling friction;N normal force;e coordinate that defines resultant reactionposition N;R radius of rolling body;G the force of gravity;α angle of inclined plane.13 th International Conference on Tribology – Serbiatrib’13 397
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SerbianTribologySocietyFacultyofEng
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Serbian Tribology SocietyUniversity
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Supported byMinistry of Education,
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PrefaceThe International Conference
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ContentsPlenary Lectures1. THE GREE
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27. WEAR CHARACTERISTICS OF HYBRID
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Tribometry57. PRELIMINARY STUDY ON
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Plenary Lectures13 th International
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Serbian TribologySocietySERBIATRIB
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Figure 4. Diagram of the height and
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Realization of the approach is base
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edge without chamfer and smaller ra
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Figure 7. Accumulated tool life in
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Figure 13. Calculated and measured
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Friction deformation of the bronze
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engine cylinders of 2-cylinder-twot
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Table 1: Chemical composition of sa
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Table 4: Comparative wear-resistanc
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- measuring of coating thickness h
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Figure 5. Functional scheme of the
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Table 2. Test results for massive w
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knowledge transfer in the field ofm
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Table 1. Parameters of the electroc
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Figure 6. Wear resistance by linear
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coatings and observed their good we
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c)a)Figure 2: SEM images and micros
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Room temperature 300°CNi/µSiCNiNi
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COF [-] COF [-]Fig.9: COF graphs at
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about 260 nm is related to isolated
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contact’s conformity [18] they ob
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In order to calculate the metallic
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microscopic inspection of the Rp3 s
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otating plate. The shaft passes thr
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similar trends of variation are obs
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smooth, gear fiber-mild steel rough
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[2] Tabor, D.: “Friction and wear
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(10, 50 and 100 N) against surface
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[9] B.R. Gligorijevic, A. Vencl, B.
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dielectric properties, high resista
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parameter, Sv, was slightly influen
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dependence of roughness height and
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Polyethylenes with a molecular weig
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[9] K.S. Kanaga Karuppiah, A.L. Bru
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MgCO3•CaCO3 (13% Mg), and carnall
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fully compatible with MRI/MSCT imag
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5. CONCLUSIONThe magnesium alloys a
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Zinc dialkyldithiophosphate (ZDDP)
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C- Lower deposits with NPNA on comb
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films. Carraro et al. [10] examined
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PlateCount No.Critical Load ( N)120
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solid melt of ZA27 alloy using mech
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SiC particles are uniformly distrib
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in number of micro-cracks and clust
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PBT has the average values of the f
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mechanical pressure and thermal loa
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3. EXPERIMENTAL RESULTSTaking into
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[12] L. Blunt De, X. Jiang: Advance
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2. EXPERIMENTALTESTING2.1 MaterialT
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figure 3a it could be seen that the
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and lubrication is done so that the
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5. CONCLUSIONFigure 11. The accumul
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esistance was found for composite c
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onze, which is embedded within the
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The test contact pair meets the req
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complete. The SEM analysis maycontr
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tg( ) tg 100, [%] (2)tgwhere are:
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corresponding to the maximum value
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electrostatics [17]. Due to the fle
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250nm size have been observed, acco
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ETH Zurich, Switzerland, where all
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comparison with the synthetic reinf
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3. RESULTS AND DISCUSSION3.1 Micros
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(a)(b)Figure 4. Showing (a) variati
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composites. But the composite compo
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coated and uncoated region after ad
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has been measured between the top s
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Fig. 9 shows the wear track obtaine
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Mica samples preparationFor the ads
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According to the AFM results in fig
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[21] B. G. Sharma et al.: Character
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chemical vapor deposition method wi
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analysis (a) and an approximate che
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Table 3. Friction coefficients of s
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A.K.Oleynik, V.M.Matsevity, ea.]. /
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Most of the friction units of produ
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In order to provide both high parts
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Fig. 3. The comparison the criterio
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Table 3. Experimental and calculate
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For developing the numerical model
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,eccentricities and hydrodynamic pr
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hydrodynamic regime. However, for b
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to obtain the temperature distribut
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force (pressure) between two contac
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5E-06The total displacement [m]4.5E
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[11]. Figure 5 shows s the influenc
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efficiency of use, product quality,
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38GSA. The chemical composition, de
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niobium. It should be noted that fo
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Figure 1. Friction force on side su
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exploitation this changing is signi
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2. EFFICIENCY OF CYCLO DRIVEEfficie
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Figure 6. Dependence of cyclo drive
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common for their ability to be inst
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FNF (11)R sin cos11 21 22FNF
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Normal force [N]4000350030002500200
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analytical tests. The analytical te
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Table 4. Results of zero samples of
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noticeable, and by the end of explo
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4. PLASTIC BEARING APPLICATIONSRega
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For Elastohydrodynamic film thickne
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The results concluded for different
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For Thrust Force of 40KNKrytox 215
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Krytox 215 (µ = 0.03204 Pa.s)Figur
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- Reliable exploitation tools, prim
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In addition, as a result of cyclic
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AcknowledgementThe part of this res
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Thepressure angle can be calculated
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mechanism these parameters are fina
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causes big changes of their propert
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Table 2. Impact toughness of some t
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Figure 1. Appearance of fractured f
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implementation of these new manugac
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additional energy is dissipated due
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The adopted geometry parameters are
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4. CONCLUSIONTools of virtual produ
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Figure 2. Structure of the machinin
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3. ANALYSIS OF RESULTSThe results o
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Figure 15. Surface roughness regard
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From the analysis of the diagram it
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comparison from economic, energy co
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Advantages and disadvantages of tra
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The information provided by footwea
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Force (N)5,554,543,532,521,510,50Ex
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additives, that had been, until rec
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Figure 1. Test results for samples
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Table 7. Test results of oil sample
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Input parameters- Current intensity
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edge formed into a thin line. At th
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Lower values of current are not res
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Table 1. Chemical composition of si
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flowable at high temperatures and v
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holes (pits) emerge in the shape of
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[4] W. Schatt, K-P. Wieters, Pulver
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assumption allows us to use, instea
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where P is the load, a - radius of
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determination (total running in tim
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μm, compared with Figure 17, wich
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Serbian TribologySocietySERBIIATRIB
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Especially when the chain transfer
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Page 367 and 368: each of which is measured by the le
Page 371 and 372: Fractal dimensions were determined
Page 375 and 376: Figure 3. Modified force acting sch
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Page 379 and 380: nanocomposites. The influence of fi
Page 381 and 382: 4. RESULTS AND DISCUSSION4.1 Morpho
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Page 389 and 390: The material after qualifying the r
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Page 393 and 394: Degradation & Stability, Vol. 69, N
Page 395 and 396: conformance to researchers’ requi
Page 397 and 398: This part is assembled of pneumatic
Page 399 and 400: matrixes describe the state of the
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Page 403 and 404: Figure 1. Friction stir weldinga -
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Page 407 and 408: M fr / T [-] [-]10.90.80.70.60.50.4
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Page 413 and 414: 4. DISCUSSIONAccording to the theor
Page 417 and 418: 2.1 The life cycle of the reportThe
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Page 425 and 426: uticaja na osnovu kompozita, a time
Page 427 and 428: 5. ZAKLJUČCIStruktura tiksolivene
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Page 431 and 432: vizuelno, na dnevnoj svetlosti, pod
Page 433 and 434: LITERATURA[1] Зинченко В.
Page 435 and 436: Slika 1. Rotorni bager - glodar VII
Page 437 and 438: stvaraju sliku stanja i svoja zapa
Page 439 and 440: njihovih kotrljanih elemenata. Mere
Page 441 and 442: postupka i uticaja parametara depoz
Page 443 and 444: posledica različite raspodele mikr
Page 445 and 446: ZrO 2 Y 2 O 3 je takođe zbog oksid
Page 449 and 450: 3.2 Pneumatska osetljivostOblast pr
Page 451 and 452: p mg (δ), koji je zbog malih struj
Page 453 and 454: PNEUMATIC PROBE HEAD SELECTION FOR
Page 455 and 456: 1. Podsistem kopanja2. Podsistem pr
Page 457 and 458: Slika 3. Kriva habanjaNa tom dijagr
Page 459 and 460: Mjereni su parametri habanja i pril
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preše prevladavaju kombinirani uvj
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a) b)Slika 5. Karakteristična mikr
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varijantnih materijala u dostavnom
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Jovanović D. 414, 446KKaleicheva J
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CIP - Каталогизација
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